Quakers Hill police station was locked down following the shooting. Photo: Ben Rushton

"The only thing I heard was the noise of the helicopter when I woke up," he said.

NSW Police Assistant Commissioner Denis Clifford said the man was involved in a confrontation with police, during which a police sergeant with 24 years' experience fired one shot at him. The man was yet to be identified, he said.

"A large knife has been located at the scene, and obviously that will be part of the investigation.

"We are trying to establish his identity and then in turn speak to relatives."

Assistant Commissioner Clifford said the officer who shot the man was "very distressed" after the incident. A number of police officers and at least one member of the public were in the area where the shooting occurred, he said.

The CareFlight helicopter landed near the shooting scene just after 11am, while a PolAir police helicopter was also circling the area.